Controlled expansion structural beam and grid



June 18, 1968 L. R. DOWNING. JR 3,388,519

CONTROLLED EXPANSION STRUCTURAL BEAM AND GRID Filed March 11, 1966 2 Sheets-Sheet 1 32 INVENTOR. L [IO LUCIE" R. DOW/7mg Jr:

ATTORNEYS June 18, 1968 R. DOWNING, JR

CONTROLLED EXPANSION STRUCTURAL BEAM AND GRID Filed March 11, 1966 2 Sheets-Sheet 2 pr-f S l zli ll nFLluun INVENTOR [ac/en A. Down/kg Jr. BY j/mw/ ydfiy ATTORNEYS United States Patent 3,388,519 CONTROLLED EXPANSSION STRUCTURAL BEAM AND GRID Lucien R. Downing, Jr., Avon Lake, Ohio, assignor to Donn Products, Inc., a corporation of Ohio Continuation-impart of application Ser. No. 407,203,

Oct. 28, 1964. This application Mar. 11, 1966, Ser- 12 Claims. (Cl. 52-495) This application is a continuation-in-part of my copending application Ser. No. 407,203, filed Oct. 28, 1964, now abandoned.

This invention relates, as indicated, to a structural beam, and more particularly to a structural beam which is characterized by means for localizing expansion causing deformation of the beam due to thermal expansion. This invention relates more specifically to a system including such structural means in combination with cross beams, of similar design, for supporting a wall, floor, or ceiling, e.g., a suspended ceiling.

The structural beam herein disclosed is an improvement on that disclosed in Patent No. 3,142,367 for Controlled Expansion Structural Beam and Grid Structure Including Same. The present invention eliminates the need for a splicing element adjacent the deformation local izing structure.

This invention will be described in relation to lightweight structural beams used in forming a grid to support a suspended ceiling, it being understood that the principles disclosed may be applied to any structural beam supporting a wall, floor, or ceiling.

The beams forming such grids are extruded or rolled from lightweight metal or thin gauge sheet metal. When exposed to high temperatures caused by, e.g., fire, the beams undergo an increase in length because of thermal expansion of the metal. Thermally induced elongation of the beam is proportional to its length. Normally, the expansion of the beams causes distortion of the grid, so much so, that panels adapted to rest on supporting flanges of the beams are no longer supported and be come free to fall from the supporting grid. In cases where fireproof panels are used, the loss of the panels exposes the superstructure to high temperatures much sooner. Therefore, it is advantageous to minimize the distortion of the grid. One way to accomplish this is to localize the expansion of the beams.

The beam disclosed in the above-mentioned patent provides means for accomplishing this, by cutting away the web of the beam at the point where it is desired to localize the expansion of the beam. However, completely cutting away the web weakens the beam at this point necessitating the use of the reinforcing member. The reinforcing member must also be designed so as not to interfere with the deformation of the beam as it expands. This not only presents a problem, but the resulting structure is somewhat complex and costly. Accordingly, it is desirable to eliminate such reinforcing means.

Although certain features of the beam disclosed in Patent No. 3,142,367 have been incorporated into the structure of this beam, it has been found that the Web need not be completely out out in order to localize deformation due to thermal expansion. By placing notches and indents in the beam, it was found that the same results were accomplished without critically weakening the beam. Beams produced in accordance herewith need no reinforcing member, and are capable of supporting a normal load.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the 'ice appended claims, the following description and annexed drawings setting forth in detail certain illustrative embodiments of the invention, such disclosed means constituting, however, but a few of the various forms in which the principle of this invention may be employed.

In the annexed drawings:

FIG. 1 is a perspective view of an embodiment of this invention showing the means for localizing the beam expansion.

FIG. 2 is a side view of the beam of FIG. 1 showing, in dotted lines, the deformed position of the flange after expansion.

FIG. 3 is a cross-sectional view taken in the plane indicated by the line 3-3 of FIG. 2, showing the deformation of the upper beaded edge upon expansion of the beam.

FIG. 4 is a cross-sectional view taken in the plane indicated by the line 44 of FIG. 2 showing the deformation of the web upon the expansion of the beam.

FIG. 5 is a top view of a portion of a grid or suspension system including thermally expansive beams in accordance herewith.

FIG. 6 is a perspective view of another embodiment of this invention.

FIG. 7 is a side view of the beam of FIG. 6.

FIG. 8 is a fragmentary side view of another embodiment of this invention.

Briefly stated, the present invention is in a controlled expansion thermally responsive structural beam including a web portion having spaced parallel marginal edges. Along one of the marginal edges, there is provided a continuous flange which may be, in certain instances, formed from an extension from the web and extending, preferably, bilaterally from the web. While there may be a similar flange disposed along the opposite parallel edge of the web, there is preferably provided, a bead or rolled over portion therealong. Means are provided in the bead or adjacent thereto for suspending or supporting the beam relative to an existing ceiling, wall, or floor structure.

Means are provided in the beam for localizing the deformation due to thermal expansion of the beam when exposed to extreme elevated temperatures. These means include means for weakening the bead or rolled over portion, by cutting a notch therein, which partially or completely traverses the bead. Also, the web is provided with a sheared or cut-out portion including a plurality of deformation localizing notches or shear lines which extend substantially to the plane of the flange. Two or three of such deformation notches may be provided. Intermediate the cutaout portion and the bead traversing notch, the web is longitudinally continuous and spans both the out-out portion and the bead traversing notch. In order to permit tearing of the web as the beam undergoes longitudinal movement due to thermal expansion, there are conveniently provided perforations along a line parallel to the longitudinal axis and adjacent the bead portion. In a preferred embodiment the perforations are a series of spaced apart lances or indents extending to either side of the bead traversing notch and extending through the web to permit tearing of the web along the line defined by the lances.

The beams herein described are adapted for use in the formation of the grid when assembled with crossing beams at spaced intervals. These crossing beams form a regular geometric pattern with the main beams of the present invention, for example, a rectangular pattern into which may be inserted corresponding geometrically shaped panels, such as, acoustic tile. The crossing beams are relatively short compared to the main supporting beams and expansion thereof is taken up at the point of intersection with the main supporting beams. Thus, a grid is provided in which the relative geometrical spacing and configuration formed by the intersecting beams is maintained even though the main beams have undergone expansion due to their much greater length and the crossing beams have undergone relatively less expansion due to their shorter length, whereby the panels are maintained in the grid and are available to serve as a thermal barrier to the supporting structure.

Referring generally to FIGS. 1-8, and more particu larly to FIGS. 17 of the annexed drawings, there is shown a lightweight structural beam generally indicated at which is normally formed from relatively thin cold rolled steel. The beam 10 has a Web 11 with spaced parallel marginal edges 8 and 9. A bilaterally extending, panel supporting flange 12 is disposed along the beams marginal edge 8. The flange 12 may be formed as an extension of the web, or independently secured as by welding to the web. A rolled bead or flange 13 is disposed along the beams other marginal edge 9. The flanges 12 and 13 are, preferably, a continuation of the web 11. A plurality of holes, e.g., holes 14, 15 and 16, are spaced along the bead 13 for receiving means, e.g., wires, for suspending the beam 10 from heavier beams, or a preformed ceiling which form the superstructure.

Any suitable means may be used to lock cross beams to the beam 10, e.g., a plurality of spaced configured holes 18 may be placed in the web 11 to receive tongue portions of the cross beams and force them into overlapped, interlocked position.

Means for localizing expansion of the structural beam will be hereinafter described in relation to the means graphically illustrated in FIGS. 1, 6 and 8. In shorter beam lengths it is desirable to use one such expansion 10- calizing means. However, in cases where the structural beams are of great length, a plurality of such means as herein described may be necessary to control the total expansion which may be as much as 1.0 to 1.5 inches in each 12-foot length.

The head 13 is interrupted by a notch 19 which preferably extends to the web 11. The notch 19 is wide enough to permit the bead portions 13a and 13b to by-pass each other as the beam 10 expands. The width W of the notch 19 along the head 13 is at least equal to the width W of the head 13 at notch 19. The head 13 is deformed at the notch 19 (FIG. 6) during the punching operation in which the notch 19 is formed. Therefore, the width W of the bead 13 at the notch 19 is usually less than the normal width W of the bead 13.

A portion 22 of the web 11, adjacent the flange 12, and in opposed relation to the notch 19, is cut out leaving a Web strap 7. The cut-out portion 22 separates the flange 12 from the web strap 7, to permit deflection of the flange 12 from the web strap 7 as the beam 10 ex pands. The longitudinal dimension of the partially cut away section 22 of the web 11 along the flange 12, is predetermined by considering the overall length of the beam in relation to a predetermined temperature and the eoeflicient of expansion of the metal. With these factors, the elongation of the beam can be determined. As previously indicated, the width of the partially cut away web portion 22 along the flange 12 is at least equal to the anticipated elongation of the beam due to expansion.

The flange 12, being of lightweight material, is apt to deflect slightly in the area of the cut-out portion 22. To prevent this, a reinforcing rib 23, which may be formed from the web itself, is provided. The rib 23 is, preferably, in the plane of the web 11, and spans the cut-out portion 22. A notch 24 is disposed in the rib 23, preferably, opposite the notch 19. The notch 24 extends substantially to the plane of the flange 12. The notch 24 is, preferably, V-shaped having its apex extending substantially to the plane of the flange 12. As more readily seen in FIG. 2, when the beam 10 expands and the flange 12 deforms (note its dotted position), the V-shaped notch 24 will partially or completely close. A pair of deflection directing notches and 21 are, preferably, provided at each end of the reinforcing rib 23. The notches 20 and 21 also extend substantially to the plane of the flange 12, to per mit controlled deflection thereof. The free marginal edge 23a of the rib 23 is adjacent the strap 7a (FIGS. 1 and 2), and, preferably, extends to and abuts the adjacent web strap edge 7a (FIGS. 6 and 7), to prevent any deflection of the flange 12, in this area, in a direction towards the web strap 7.

Extending from the notch 19 adjacent the head 13, are a plurality of indents, perforations or lances, e.g., indents 25, 26, 27, 28, 29 and 30, which are punched into the web strap 7 to weaken the web strap 7 to permit tearing of the web strap 7 along the indents -30. The indents, preferably, extend along a line spanning the notch 19, a distance such, that their overall longitudinal extent is approximately equal to the overall longitudinal extent of the cut away portion 22 in the web 11. As more readily seen in FIGS. 3 and 4 when the beam 10 expands, the web 11, at the point of localizing, will expand over itself, or roll over itself forming an S-curve as seen in FIG. 4.

The bead 13 is too rigid to roll over itself. Therefore, the bead 13 must be notched and indents placed in the web 11 at this point to permit the confronting ends of the head 13 to tear themselves from the weakened web along the line of indents or cuts 25-30, and slide by each other as shown in FIG. 3. As the beam expands, the web portion 11 rolls over itself and bead 13, on each side of. the notch 19, bypasses itself. The now overlapping bead portions 13a and 13b are held close together by the action of the web strap 7 in folding back upon itself. Thus, the spacing between adjacent main beams in a grid structure is maintained nearly constant, and the panels continually upported.

Referring to FIG. 5, a grid or suspension system is shown comprising a plurality of main supporting beams, e.g., beams 10, in parallel spaced relation, being intersected by a plurality of cross beams, e.g., beams 31, at right angles thereto, to form a predetermined geometric configuration. The beams 31 are joined to the beams 10 by any suitable means, e.g., holes 18 spaced along the web 11. In the grid or suspension system, the means for localizing expansion illustrated in FIGS. 1, 6 and 8 are indicated at 32, and are preferably in predetermined alignment, to permit uniform expansion of the entire grid or suspension system. As previously indicated, the cross beams 31 are relatively short in comparison to the main beams 10, and means are provided thereon for expansion at the point of intersection with the main beam 10. In cases where the cross beams 31 are long enough to require means for localizing their expansion, means for localizing similar to means 32, may be placed in the cross beams 31 in similar predetermined alignment. The cross beams may be of conventional design for such members.

The embodiment of the invention illustrated in FIG. 8 similarly employs a notched head 13 having cuts or indents 25-30 for weakening the web strap 7. However, in this particular embodiment the cut away portion 22 and rib 23 are defined by cuts or shear lines 35-37, which are punched or placed in the web 11. Simultaneously the rib 23 is cut or sheared along line 38 which is, preferably, opposite the bead notch 9, and divides the rib 23 into two rib portions 39 and 40. The cuts 35, 37 and 38, are, prefer ably, parallel and extend substantially to the plane of the panel supporting flange 12. The shear lines or cuts 35, 37 and 38 act in relatively the same manner as the notches 20, 21 and 24, in that they permit the rib portions 39 and 40 to deflect with the flange 12, by rotating about the junction points 41 and 42, respectively, that the cuts 35 and 37 make with the flange 12. The rib portions 39 and 40 will either by-pass or partially overlap each other as they rotate about points 41 and 42, or being in aligned, abutting relation will, because of the lightweight metal used in forming the beam 10, readily deform not to impede the deflection of the flange 12 and the deformation of the web strap 7.

Thus, there has been provided a highly improved structural beam member characterized by controlled expansion, whereby the expansion due to an increase in temperature is localized in a portion of the beam. By providing such means in aligned planes in beams forming a grid or suspension system, the geometric configuration formed thereby is relatively unchanged upon expansion.

The improved structure of the beam eliminates the need for a reinforcing member. Thus, a simpler, more economical structural beam is provided.

Other modes of applying the principle of this invention may be employed instead of those specifically set forth above, changes being made as regards the details herein disclosed, provided the elements set forth in any of the following claims, or the equivalent of such, be employed.

It is, therefore, particularly pointed out and distinctly claimed as the invention:

1. A self-supporting, unitary controlled expansion thermally responsive structural beam comprising:

(a) a Web having spaced parallel marginal edges;

(b) a flange disposed along at least one of the marginal edges;

(c) a portion of the web, adjacent the flange, having cut therein a plurality of deflection directing notches angularly disposed to the flange, the notches being connected at one extremity, and having their other extremities extending to the plane of the flanges, the remaining portion of the web adjacent the other marginal edge, spanning the notches.

2. The beam of claim 1, wherein the notches are at right angles to the flange.

3. A self-supporting, unitary controlled expansion thermally responsive structural beam comprising:

(a) a web having spaced parallel marginal edges, one marginal edge being rolled to form a reinforcing bead, the bead having a notch therein extending to the web;

(b) a bilaterally extending flange disposed along the other marginal edge of the web, the flange being an extension of the web;

(c) a portion of the web, adjacent the flange and in opposed relation to the notch in the bead, being cut away to permit deflection of the flange therefrom as the beam expands, and the remaining portion of the web adjacent the bead, spanning the cut-away portion;

(d) means, in the web adjacent the bead and extending from the notch, for weakening the web to permit tearing therealong as the beam expands, to allow the bead ends adjacent each side of the notch to by-pass each other as the beam expands.

4. The beam of claim 3 wherein the cut-away portion extendssubstantially to the plane of the flange.

5. The beam of claim 4, wherein the means (d) for weakening the web includes indents punched into the web adjacent the head, the indents being longitudinally substantially coextensive with the cut-away portion.

6. The beam of claim 5, which includes a rib for reinforcing the flange adjacent the cut-away portion of the web, to keep the flange from deflecting under normal loads, the rib at least partially spanning the cut-away portion and having at least a cut therein extending substantially to the plane of the flange, to allow the flange, adjacent the cut-away portion, to deflect as the beam expands.

7. A self-supporting, unitary controlled expansion thermally responsive structural beam comprising:

(a) a web having spaced parallel marginal edges, one marginal edge being rolled to form a reinforcing head, the bead having a notch therein extending to the web;

(b) a bilaterally extending flange disposed along the other marginal edge of the Web, the flange being an extension of the web;

(c) a portion of the web, adjacent the flange and in opposed relation to the notch in the bead, having cut therein a plurality of deflection directing notches being connected at one extremity and having their other extremities extending substantially to the plane of the flange, the remaining portion of the Web adjacent the bead, spanning the notches;

(d) means, in the web adjacent the bead and extending from the notch, for weakening the web to permit tearing therealong as the beam expands, to allow the bead ends adjacent each side of the notch to by-pass each other as the beam expands.

8. A grid system for supporting a plurality of panel members in a common plane comprising:

(a) a plurality of main beams disposed in spaced parallel relation, each of the main beams comprising:

(i) a web having spaced parallel marginal edges;

(ii) a reinforcing bead along one marginal edge, the bead having a notch therein extending to the web;

(iii) a bilaterally extending flange disposed along the other marginal edge of the web, the flange being an extension of the web;

(iv) a portion of the web adjacent the flange and in opposed relation to the notch in the bead, being cut away to permit deflection of the flange when the beam expands, the cut-away portion extending substantially to the plane of the flange, the remaining portion of the web adjacent the bead, spanning the cut-away portion;

(v) a plurality of indents punched in the Web adjacent the bead and extending from the notch, for weakening the web to permit tearing therealong as the beam expands to allow the beads adjacent each side of the notch to by-pass each other as the web rolls over itself in response to beam expansion;

(vi) a reinforcing rib integral with the flange, in

the plane of the web adjacent the cut-away portion of the web, to keep the flange from deflecting under normal loads, the rib having therein opposite the notch in the bead, a V-shaped notch with its apex extending substantially to the plane of the flange, to permit deflection of the flange when the beam expands;

(b) a plurality of cross beams disposed in spaced parallel relation transverse to the main beams and defining a geometric configuration therewith, each of the cross beams having:

(i) a web having spaced parallel marginal edges;

(ii) a bilaterally extending flange disposed along one marginal edge for coaction with the flange 0f the main beam to provide peripheral support for the panel members;

(iii) means at their extremities, for interlocking coaction with the main beams;

(iv) means coacting with the interlocking means in response to expansion of the main and cross beams to maintain the predetermined geometric grid configuration Without disturbing the panel members supported thereby; and

(c) a plurality of panel members inserted in the openings formed by the intersecting beams and supported on the flanges thereof.

9. In a beam having:

(a) a web with spaced parallel marginal edges;

(b) a reinforcing flange along one marginal edge;

(e) a bilaterally extending flange for supporting panels,

along the other marginal edge;

(d) a portion of the web adjacent the panel supporting flange out such that two spaced points on said flange will move towards each other as said flange, between said points, deflects out of the flange of said flange 7 in a direction away from the opposing reinforcing flange; the improvement which includes:

(e) a notch in the reinforcing flange, extending at least to theweb; and

(f) indents in the web adjacent the reinforcing flange,

and extending from the notch for weakening the web to allow the reinforcing flange to tear itself from the web as the beam expands and the panel supporting flange deflects.

10. In a beam including means for localizing longitudinal thermal expansion, said beam having a web, at least one laterally extending panel supporting flange along one marginal edge of said web and including a cut-out portion of the Web adjacent the flange and a notch extending into the opposite marginal edge of said web in opposed relation to the cut-out web portion, the improvement which comprises a separable strap portion of said Web integral therewith and spanning said cut-out portion, means for separating said strap portion from said web in response to thermal expansion of the beam whereby opposing ends of said opposite marginal edge on each side of the notch by-pass each other.

11. The beam expansion localizing means of claim 10, wherein the strap separating means includes a plurality of longitudinally directed aligned indents spanning said cut-out portion.

12. The beam expansion localizing means of claim 11, wherein the line of said indents is intersected by said notch.

References Cited UNITED STATES PATENTS 3,142,367 7/1964 Brown et a1. 52-573 3,159,252 12/1964 Cotts 52-573 3,175,655 3/1965 Brown et a1. 52-573 3,189,138 6/1965 Znamirowski 52-573 3,189,139 6/1965 Znamirowski 52-573 HENRY C. SUTHERLAND, Primary Examiner.

J. L. RIDGILL, JR., Examiner. 

1. A SELF-SUPPORTING, UNITARY CONTROLLED EXPANSION THERMALLY RESPONSIVE STRUCTURAL BEAM COMPRISING: (A) A WEB HAVING SPACED PARALLEL MARGINAL EDGES; (B) A FLANGE DISPOSED ALONG AT LEAST ONE OF THE MARGINAL EDGES; (C) A PORTION OF THE WEB, ADJACENT THE FLANGE, HAVING CUT THEREIN A PLURALITY OF DEFLECTION DIRECTING NOTCHES ANGULARLY DISPOSED TO THE FLANGE, THE NOTCHES BEING CONNECTED AT ONE EXTREMITY, AND HAVING THEIR OTHER EXTREMITIES EXTENDING TO THE PLANE OF THE FLANGES, THE REMAINING PORTION OF THE WEB ADJACENT THE OTHER MARGINAL EDGE, SPANNING THE NOTCHES. 